The present invention relates to a player for video or compact disks. More specifically, the invention relates to such a player having an improved function of starting the playing of a disk, particularly, a CLV (Constant Linear Velocity) type disk played at a nonconstant angular velocity, at other than its ordinary beginning position.
It is often desired to start the play of a disk at other than its ordinary beginning position, for instance, to start the play of an audio disk at a particular musical selection. In the conventional player, it is necessary to first start the play of the disk from its ordinary beginning position, then perform a search operation to locate the start position of the desired selection. More specifically, the disk is first set on the turntable and the PLAY button or the like is depressed, whereupon the disk starts rotating. The pickup (playback head) is then moved from its rest (parked) position slightly outside of one of the inner and outer edges of the area where data is recorded on the disk to the start position on the disk where control codes and the like are recorded prior to the start of the other recorded data. The focus and tracking servo systems are then actuated. Next, a control code is read from the start position of the disk to determine whether the disk is recorded in the CLV mode of the CAV (Constant Angular Velocity) mode. Subsequently, the start address of the desired selection is searched for. When this start address is reached, play of the disk is commenced in the specified mode.
The desired playback start position is specified in the form of chapter, frame and time numbers. A microprocessor contained in the control unit for the player instructs the carrying out of the search operation using this data. In doing so, the pickup is moved in the radial direction of the disk from the innermost or outermost edge of the area where information is recorded to the indicated start position, reading out chapter numbers as it is moving. Upon arriving at the specified start position, the spindle servo (which controls the rotational speed of the disk) is locked and the disk is rotated at the appropriate speed for the location of the pickup.
In this operation, start and then search movements must be performed sequentially. As a result, much time passes before the playing of the desired selection can begin. In a player in which the parked position of the pickup is at the inner periphery of the disk, as much as 30 seconds may pass before a desired selection can be played, about 15 seconds for the start operations and about another 15 seconds for the search operation in the case of a 30 cm CLV disk.
It is of course possible to reduce these times by merely providing a motor having a higher torque output, and accordingly employing more sturdy associated components used in rotating the disk and moving the pickup. Doing so, however, is unavoidably costly. Moreover, there is a limit as to how much the starting time can be reduced due to difficulties in reading address information from the disk as its speed is increased.